A single missed handshake between a ground handler and a control tower can push a flight’s departure back by minutes that never get recovered. Multiply that across a busy hub at peak times and the ripple reaches gates, stands and connecting passengers who never see the cause. EUROCONTROL’s impact assessment of seventeen fully implemented CDM airports found that take-off time predictability improved by as much as 85% during adverse conditions once these airports adopted a shared timeline for departures. That single figure shows why TOBT and TSAT have become central to how modern airports manage flight turnaround time and keep departures on track.
This article works through what TOBT and TSAT mean, why airports build an entire framework called Airport Collaborative Decision Making around them and what it takes on the technology side to make that framework hold together during daily operations.
Breaking down TOBT and TSAT
TOBT is the Target Off-Block Time. It’s the moment a ground handler or airline operations team estimates an aircraft will be fully ready, doors shut, bridge clear, pushback vehicle in position, waiting only on clearance from the control tower. Nobody guesses at this. Ground teams update it continuously as boarding, fuelling and baggage loading progress. Airports typically expect that estimate to hold within five minutes of accuracy.
TSAT, the Target Start-up Approval Time, comes next. Once air traffic control has a TOBT, it factors in runway sequencing, air traffic flow restrictions and ground congestion to issue a TSAT: the window in which an aircraft can request pushback. TOBT tells the airport when a flight will be ready. TSAT tells it when the system can let that flight go.
The problem this framework was built to solve
Before this kind of shared timeline existed, every stakeholder at an airport worked from their own version of the truth. Ground handlers tracked turnaround progress on their own systems. Airlines held their own estimates. Air traffic control worked from scheduled times that rarely reflected what was happening on the apron. Nobody was looking at the same picture.
Airport Collaborative Decision Making, or A-CDM, exists to close the gaps. It’s a joint framework developed by EUROCONTROL, ACI Europe, IATA and CANSO, and it treats a flight’s turnaround as one continuous process rather than a set of disconnected handoffs between ground handling, airline ops and the control tower. Every partner works from the same milestone data, updated in real time, rather than reconciled spreadsheets.
The numbers back this up. The same EUROCONTROL study found that airports using full A-CDM reduced taxi-out times by an average of three minutes per flight. They also saw fewer last-minute stand and gate changes, and made better use of their ground handling staff and equipment. This is achieved by everyone working off one clock instead of five.
How the timeline moves
The sequence runs in a straightforward line, even though the coordination behind it isn’t simple. Ground handling starts with the handler filing an initial TOBT approximately twenty-five minutes before departure. As boarding, catering and baggage loading progress, the TOBT is revised whenever the estimate moves by more than a couple of minutes. The tower takes the TOBT, layers in runway demand and any flow restrictions from the network, and returns a TSAT. The crew requests pushback within that window and only at that point is the actual off-block time recorded.
What makes this valuable is that everything downstream – stand allocation, apron monitoring, baggage systems – gets an accurate, shared estimate instead of a static scheduled time that stopped being reliable the moment a flight from somewhere else landed late.
Why A-CDM depends on system integration, not just process
A-CDM only works if the underlying systems can talk to each other. A ground handling platform that can’t pass TOBT updates to the control tower’s system in real time creates the fragmented picture A-CDM was designed to remove. This is where system integration becomes the essential layer underneath the framework: flight information systems, resource management tools and apron control all need to draw from one consistent data source.
A-CDM pays off for airports when they treat it as a joint technology and operations management effort, not a list of individual system upgrades. Airports that bolt a TOBT feed onto legacy infrastructure tend to get less value.
The human side of the discipline
Nothing replaces the judgement of ground teams, tower controllers or airline operations staff. A TOBT is only as good as the person entering it, and a TSAT only works if ground handlers plan pushback around it rather than treating it as a suggestion. The technology gives these teams a shared, accurate picture. It doesn’t make the decisions for them. Airports that get real value from A-CDM train their people to trust the timeline and act on it early.
WAISL’s system integration approach helps airports bring ground handling, air traffic data and resource planning onto one connected timeline, turning TOBT and TSAT from paperwork into operational advantage. Get in touch with our team to learn more.
